The field of invention relates generally to imprint lithography. More particularly, the present invention is directed to forming layers on a substrate to facilitate fabrication of high resolution patterning features suited for use as metrology standards.
Metrology standards are employed in many industries to measure the operation of varying equipment and processes. For semiconductor processes, a typical metrology standard may include grating structures, L-shaped structures and other common patterning geometries found on production devices. In this manner, the metrology standards facilitate measurement of the performance of the processing equipment.
Conventional metrology standards are manufactured from a variety of conventional processes, such as e-beam lithography, optical lithography, and using various materials. Exemplary materials include insulative, conductive or semiconductive materials. After formation of the metrology standards using conventional processes, a post process characterization technique is employed to measure the accuracy of the metrology features. This is due, in part, to the difficulty in repeatably producing reliable accurate metrology standards. A drawback with the conventional processes for manufacturing metrology standards is that the post process characterization step is time consuming. In addition, the difficulty in repeatably producing reliable metrology standards results in a low yield rate. A processing technique that may prove beneficial in overcoming the drawbacks of the conventional processes for fabricating metrology standards is known as imprint lithography.
An exemplary imprint lithography process is disclosed in U.S. Pat. No. 6,334,960 to Willson et al. Willson et al. disclose a method of forming a relief image in a structure. The method includes providing a substrate having a planarization layer. The planarization layer is covered with a polymerizable fluid composition. A mold makes mechanical contact with the polymerizable fluid. The mold includes a relief structure, and the polymerizable fluid composition fills the relief structure. The polymerizable fluid composition is then subjected to conditions to solidify and polymerize the same, forming a solidified polymeric material on the planarization layer that contains a relief structure complimentary to that of the mold. The mold is then separated from the solid polymeric material such that a replica of the relief structure in the mold is formed in the solidified polymeric material. The planarization layer and the solidified polymeric material are subjected to an environment to selectively etch the planarization layer relative to the solidified polymeric material such that a relief image is formed in the planarization layer. Advantages with this imprint lithography process are that it affords fabrication of structures with minimum feature dimensions that are far smaller than is provided employing standard semiconductor process techniques.
It is desired, therefore, to provide a method for reliably producing precision features on a substrate for use as metrology standards.